應用二位元相移調變於發射源及彎折偶極子天線於接收端以達成穩定遠場無線功率傳輸系統

Abstract

本論文針對UHF頻段915 MHz無線功率傳輸 (wireless power transfer, WPT) 系統中進行發射訊號與天線之設計、模擬與量測分析。本論文首先介紹無線功率傳輸系統之基本架構與工作原理，並探討輸入訊號音調數以及不同調變訊號對整流器能量轉換效率 (power conversion efficiency, PCE) 的影響。在發射源部分，本論文採用二位元相位偏移調變 (binary phase shift keying, BPSK) 與隨機BPSK搭配連續波以分析訊號之峰均功率比 (peak-to-average power ratio, PAPR) 對整流效率之影響，並發現隨機BPSK訊號搭配連續波由於高PAPR造成整流效率較純連續波輸入提升4%左右。在天線設計方面，使用彎折偶極子作為接收端以縮小尺寸，整體實作於5 cm × 5 cm的FR-4板上，最大增益約為 -7 dB，並透過調整天線參數以在阻抗匹配與增益之間取得平衡。最後將天線與整流器整合並進行量測，探討不同調變訊號與功率比例對整流效率的影響，並發現雙音調訊號整流效率在不同輸入功率下比單音調訊號皆高出4%左右。在雙音調相同總功率訊號輸入下，兩訊號功率比例為1:1時PAPR為最高因而整流效率較單音調輸入高出2%左右。

This thesis investigates the design, simulation, and measurement of transmission signals and antennas for a 915 MHz ultra-high-frequency (UHF) wireless power transfer (WPT) system. First, the fundamental architecture and operating principles of WPT systems are introduced, followed by an investigation into the effects of the number of input tones and different modulation schemes on the power conversion efficiency (PCE) of rectifiers. On the transmitter side, binary phase shift keying (BPSK) and random BPSK combined with a continuous wave (CW) are employed to analyze the influence of the peak-to-average power ratio (PAPR) on rectification efficiency. Experimental results show that, due to its higher PAPR, the random BPSK signal combined with a CW input improves the rectification efficiency by approximately 4% compared with a pure CW input. For the antenna design, a meander dipole antenna is adopted as the receiving antenna to achieve size reduction. The antenna is implemented on a 5 cm × 5 cm FR-4 substrate, achieving a maximum gain of approximately -7 dB. By adjusting the antenna parameters, a trade-off between impedance matching and antenna gain is achieved. Finally, the antenna is integrated with the rectifier and experimentally evaluated the effects of different modulation schemes and power ratios on rectification efficiency. Measurement results indicate that the rectification efficiency of two-tone signals is approximately 4% higher than that of single-tone signals across different input power levels. Under the condition of equal total input power for the two-tone signals, a 1:1 power ratio yields the highest PAPR, resulting in a rectification efficiency approximately 2% higher than that of single-tone input.